The technical challenge at the heart of the study is that autophagy is notoriously difficult to measure in living humans. Macroautophagy is a multi-step process in which cellular cargo is sequestered into double-membraned vesicles called autophagosomes and delivered to lysosomes for degradation. Common laboratory readouts, such as the abundance of autophagosomes or levels of the autophagosome-associated protein LC3/Atg8-II, are static snapshots that cannot distinguish a cell cranking out autophagosomes from one whose degradation machinery has stalled. The gold-standard approach, pharmacologically blocking lysosomal degradation and watching cargo accumulate, is not feasible in vivo in people. The research team therefore built a multi-pronged strategy using accessible human cells that retain molecular signatures of their donors’ ages.

The team worked with three complementary cell systems drawn from the well-characterized SHOCK healthy aging cohort, whose participants self-report freedom from chronic disease. Low-passage primary dermal fibroblasts from the skin preserve transcriptional signatures of aging. From those same fibroblasts, the researchers generated induced neurons, or iNs, by directly converting the cells with the neuronal transcription factors NGN2 and ASCL1, creating subject-matched pairs of skin and nerve cells. Finally, they isolated peripheral blood mononuclear cells, or PBMCs, freshly drawn from participants, a minimally invasive window into autophagy in circulating T, B, and NK cells. Measuring all three cell types from overlapping groups of donors allowed the investigators to ask whether autophagy is coordinated across a single individual’s body or regulated independently in each tissue.

The first surprise came from transcription. In fibroblasts from older donors, bulk RNA sequencing revealed broad upregulation of autophagy-related gene programs: modules for macroautophagy, autophagosome assembly, and autophagosome maturation were significantly enriched with age, alongside classic senescence-associated signals such as TNFα, IL6-JAK-STAT3, and p53 signaling. Individual genes behaved heterogeneously, with some, including ATG5 and ATG7, decreasing while most macroautophagy genes rose or peaked in mid-to-late adulthood. In iNs, the pattern was weaker and more scattered; autophagy-related pathways were enriched at the pathway level, but curated gene modules were not significantly changed. If transcription were destiny, one would expect both cell types to show boosted autophagic activity. They did not.

Functional measurements told a very different story. Using chloroquine to block lysosomal degradation for two hours and quantifying the resulting accumulation of LC3B-positive structures, the researchers calculated autophagy flux, the true throughput of the pathway. A critical methodological finding emerged immediately: static LC3B-positive foci did not correlate with flux in any cell type, confirming that autophagosome abundance alone is an unreliable proxy for autophagic activity. Flux, not abundance, is what matters, and flux behaved in ways the transcriptomic data could not have predicted.

In fibroblasts, autophagy flux was sex-specific. Young male donors’ fibroblasts trended toward higher flux than young female donors’, but with age the pattern reversed: flux declined significantly in cells from males, while remaining stable in cells from females, so that older donors of both sexes converged. A multiple linear regression with an age-by-sex interaction confirmed that age was significantly associated with declining flux in males, with the interaction term trending toward significance. In induced neurons, the pattern flipped again. Neuronal flux was stable with age in cells from males but increased with age in cells from females, a significant age-by-sex interaction. When the researchers compared subject-matched fibroblasts and iNs from the same donors, flux in one cell type did not predict flux in the other, demonstrating that autophagy is not coordinately regulated across tissues within an individual.

PBMCs added a third pattern. Across twenty-three participants spanning ages twenty-four to eighty, autophagy flux in fresh immune cells showed no significant association with chronological age and no sex differences. What changed instead was variability: flux became markedly more heterogeneous with advancing age, with a trend toward higher values in individuals around seventy and older. This echoes recent independent reports that autophagy flux in freshly isolated PBMCs can rise with age. The researchers verified that the findings were not artifacts of age-related shifts in immune cell composition, either in whole blood or after isolation.

The most provocative results connected these cellular measurements to whole-body physiology. SHOCK participants underwent standardized fitness assessments, including maximal treadmill testing for VO2max, grip strength, walking speed, blood pressure, and the Short Physical Performance Battery. Across the full cohort, the correlations between flux and fitness varied by cell type: higher flux in fibroblasts and PBMCs sometimes tracked with more youthful cardiovascular measures, such as higher maximum heart rate and lower resting heart rate, while higher flux in iNs correlated with weaker grip strength and slower walking speed. But when the analysis focused on participants aged seventy and older, a consistent picture emerged: higher autophagy flux in all three cell types was associated with reduced physical function. Higher PBMC flux accompanied lower VO2max, slower walking speed, and longer chair-stand times; higher fibroblast flux accompanied reduced resting VO2; and higher iN flux accompanied dramatically reduced maximal grip strength. The authors caution that these subgroup correlations rest on small samples, but the direction was strikingly uniform.

Why would elevated recycling signal decline rather than resilience in the oldest adults? The authors propose that the meaning of high flux depends on context. In younger people, high flux may reflect abundant autophagic capacity, a well-oiled maintenance system. In the very old, elevated flux may instead represent increased autophagic demand, a compensatory response to accumulating cellular stress and damage, or a struggle to keep pace with degradation needs. This reframing carries real consequences for interventions. Strategies aimed at simply boosting autophagy, whether pharmacological or dietary, may need to account for biological age and tissue context, because pushing flux higher in an eighty-year-old could be counterproductive if the elevation already reflects stress rather than capacity.

The study’s final act tested whether the system is modifiable. In a pilot within the STRONG fall-prevention exercise cohort, five participants aged seventy-seven to eighty-eight completed twelve weeks of mild exercise, one-hour weekly sessions focused on balance, strength, and posture. At baseline, four of the five showed PBMC autophagy flux more than one standard deviation above the SHOCK cohort mean, consistent with the link between elevated flux and reduced function. After the program, flux decreased in four of five participants, falling back within one standard deviation of the younger cohort average, while SPPB scores improved. Immune cell composition was unchanged, suggesting the effect was not a shift in cell populations. Intriguingly, the single participant whose flux rose was the youngest and most physically capable at baseline. The sample is tiny and the timepoints limited, but the implication is bold: autophagy flux in human immune cells is not a fixed consequence of aging but a dynamic, responsive parameter, one that mild exercise can nudge back toward a youthful setpoint while physical performance improves. Larger studies with frailty indices, cognitive measures, and single-cell resolution will be needed to confirm when rising flux is beneficial and when it is a warning light, but this work makes clear that the old dogma of universal autophagic decline cannot survive direct measurement.

Subject of Research: Sex- and cell-type-specific remodeling of autophagy flux during human aging and its relationship to physical function

Article Title: Autophagy Flux Is Remodeled Sex‐ and Cell Type‐Specifically During Human Aging, and Is Linked to Reduced Physical Function in Older Adults

Article References: Moreno, T. M., Heimler, S. R., Moran, R. J., Barkai, H. S., Scandalis, L., Traxler, L., Neil, A., Dozier, S., Bergstrom, J., Colas, A. R., Ranade, S. S., Bang, A. G., Mertens, J., Wing, D., Molina, A. J., & Kumsta, C. (2026). Autophagy Flux Is Remodeled Sex‐ and Cell Type‐Specifically During Human Aging, and Is Linked to Reduced Physical Function in Older Adults. Aging Cell, 25(10), Article e70734. https://doi.org/10.1111/acel.70734

Image Credits: AI Generated

DOI: 10.1111/acel.70734

Keywords: autophagy, aging, autophagy flux, induced neurons, fibroblasts, PBMCs, physical function, exercise, chloroquine assay, LC3B, sex differences, healthy aging

Noncoding RNAs have emerged over the past two decades as master regulators of gene expression. Unlike messenger RNAs, they do not encode proteins, yet they exert profound influence over which genes are switched on, silenced, or fine-tuned. Among them, circular RNAs, or circRNAs, form closed loop structures that resist degradation and often act as molecular sponges that sequester microRNAs. Long noncoding RNAs, or lncRNAs, participate in chromatin remodeling, transcriptional control, and scaffolding of regulatory complexes. Through the competing endogenous RNA, or ceRNA, hypothesis, circRNAs and lncRNAs can indirectly modulate protein output by titrating away miRNAs that would otherwise suppress target messenger RNAs. When those targets happen to be autophagy-related genes, the result is a potential regulatory network capable of dialing cellular self-digestion up or down during development. Precisely how such a network operates in the human fetal intestine had never been systematically explored.

The research team, led by Si Ying Li and corresponding author Yu Zuo Bai, approached the problem with an unusually comprehensive toolkit. They performed high-throughput sequencing on ten human fetal intestinal samples spanning 7 to 20 post-conception weeks, a period during which the gut undergoes dramatic morphological and functional transformation, from initial tube formation through epithelial differentiation and the onset of digestive capacity. By profiling the expression of autophagy-related circRNAs and lncRNAs across these developmental stages, the researchers could construct predicted regulatory networks linking each noncoding RNA to microRNAs, messenger RNAs, and ultimately the autophagy machinery itself. Expression was quantified in standardized units such as FPKM, fragments per kilobase of transcript per million mapped reads, allowing rigorous comparison across samples and time points.

The sequencing data revealed clear temporal dynamics: the population of autophagy-associated noncoding RNAs was not static but changed measurably as gestational age advanced, suggesting that different regulatory circuits dominate at different phases of intestinal maturation. Notably, the analysis identified multiple previously unreported noncoding RNAs in the fetal intestine, transcripts that had simply not been cataloged in this tissue before. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses, together with protein-protein interaction mapping, helped situate these transcripts within biologically meaningful networks centered on lysosomal degradation, vesicle formation, and cellular remodeling. In effect, the study produced a developmental atlas of the RNA regulators that may govern how fetal intestinal cells recycle themselves as they differentiate.

Because predicted networks alone cannot demonstrate that autophagy is actually altered, the team turned to direct structural and protein-level evidence. Using transmission electron microscopy on intestinal duplication samples, rare congenital malformations in which a duplicated segment of bowel forms alongside the normal tract, the researchers observed autophagy-related ultrastructural alterations when compared with normal postnatal intestinal controls. Electron microscopy is the gold standard for visualizing autophagosomes, the double-membraned vesicles that engulf cellular cargo before delivery to lysosomes, and their altered abundance or morphology in the duplication samples pointed to genuine perturbation of the pathway in this developmental anomaly rather than a purely theoretical regulatory link.

Immunohistochemistry reinforced this conclusion with complementary protein markers. LC3B, the lipidated form of the LC3 protein that decorates mature autophagosomal membranes, was expressed at higher levels in the intestinal duplication group, while P62, also known as SQSTM1, an adaptor protein that accumulates when autophagic flux is impaired, was lower. The combination of elevated LC3B and reduced P62 provides a characteristic signature that helps distinguish between active flux and blocked degradation, and its presence in duplication samples suggests that autophagy is dynamically engaged in these malformations. Fluorescence in situ hybridization paired with immunofluorescence double staining then allowed the researchers to visualize, in intact tissue sections, the co-expression of core noncoding RNAs and their predicted target proteins, anchoring the computational networks to spatial reality within the developing gut wall.

What makes this work particularly compelling is the convergence of scales. At the transcriptomic level, the study captures thousands of noncoding RNA species rising and falling across thirteen weeks of development. At the ultrastructural level, electron micrographs show autophagic vesicles behaving differently in malformed versus normal tissue. At the protein level, immunostaining confirms that the canonical autophagy markers shift in the predicted directions. And at the cellular level, co-localization experiments place specific regulatory RNAs in the same cells as their presumed protein targets. This multi-layer validation strategy is exactly what the ceRNA field has often been criticized for lacking, and it lends substantial credibility to the predicted networks the authors constructed.

The clinical implications extend beyond basic developmental biology. Intestinal duplications are congenital anomalies whose molecular origins remain poorly understood, and this study is among the first to implicate dysregulated autophagy, and the noncoding RNAs that may regulate it, in their pathogenesis. If specific circRNAs or lncRNAs prove to be causally involved rather than merely correlated, they could become diagnostic biomarkers identifiable in prenatal screening or, more speculatively, therapeutic targets capable of modulating autophagic flux during critical windows of organogenesis. The authors themselves frame their findings as a foundation for future studies of embryonic developmental disorders, a deliberately measured claim that reflects both the promise and the preliminary nature of the work.

There are, of course, important caveats. The sample size of ten fetal intestinal specimens, while substantial for human prenatal tissue, which is ethically and logistically difficult to obtain, still limits statistical power and generalizability. The regulatory networks are predictive, built on established miRNA-target databases and expression correlations, and ceRNA interactions in particular require functional validation through perturbation experiments before they can be considered proven mechanisms. The comparison of fetal duplication tissue with postnatal controls also introduces an age difference that the authors acknowledge through their careful design, but developmental stage remains a variable that future work will need to disentangle. Ethical oversight was rigorous, with approval from the Ethics Committee of China Medical University and written informed consent from all participants, and the study was supported by the National Natural Science Foundation of China and the Liaoning Province Science and Technology Plan Joint Project.

Even with these limitations, the study marks a significant advance. It demonstrates that the noncoding RNA dimension of autophagy regulation is active and dynamic during precisely the developmental window when the human intestine acquires its structure and function, and it delivers a catalog of novel fetal intestinal transcripts that other labs can now interrogate. As single-cell sequencing and functional perturbation technologies continue to mature, this atlas provides the scaffolding on which causal studies can be built. For now, the work stands as a vivid reminder that the blueprint of human development is written not only in protein-coding genes but in the vast, looping, and still largely mysterious world of noncoding RNA, and that the cellular recycling system it governs may hold clues to some of the earliest origins of congenital intestinal disease.

Subject of Research: Autophagy-related noncoding RNA regulation during human prenatal intestinal development

Article Title: Dynamic expression of noncoding RNAs associated with autophagy-related genes in the human intestine during prenatal development

Article References: Li, S. Y., Wu, M. Y., Liu, S. T., Wang, C. Y., Tang, X. B., & Bai, Y. Z. (2026). Dynamic expression of noncoding RNAs associated with autophagy-related genes in the human intestine during prenatal development. BMC Genomics. https://doi.org/10.1186/s12864-026-13403-5

Image Credits: AI Generated

DOI: 10.1186/s12864-026-13403-5

Keywords: autophagy, noncoding RNAs, circRNA, lncRNA, miRNA, fetal intestine, prenatal development, intestinal duplication, RNA sequencing, ceRNA, LC3B, P62